Automatic dispensing nozzle

ABSTRACT

An automatic fuel tank filling nozzle which, in addition to a main valve which automatically closes in response to a suction set up by the rise of fluid about the end of the nozzle, comprises a rotary flow-regulating valve having two alternate rotational positions, one permitting full flow of fuel thru the nozzle and the other permitting only a restricted flow suitable for topping, the rotary valve being rotated into the next alternate position in response to each vacuum signal whereas the main control valve is responsive only to the signal which follows the end of the topping operation.

full flow of um signal the signal -regulating valve having s t llllllEss ' all United States Patent [72] Inventors 8/1960 Rittenhouse et al.

Eugene w. Vest 2,948,307 Wnpplngers Falls; 3,254,683 6/l966 Jennings etal. 2 A l N g gf g bow Primary Examiner-Laverne D. Geiger Oct 29 1969Assistant Examiner-Edward J. Earls b patented jim'e 5 Attorneys'l'homasH. Whaley, Carl G. Ries and L. H. Phelps, [73] Assignee Texaco lne.

New York, N.Y.

[54] AUTOMATIC DISPENSING NOZZLE 6 Claims, 8 Drawing Figs.

ABSTRACT: An automatic fuel tank filling nozzle which, in

addition to a main valve which automatically closes in response to asuction set up by the rise of fluid about the end of the nozzle,comprises a rotary flow two alternate rotational positions, onepermitting fuel thru the male and the other permitting only a restrictedflow suitable for topping, the rotary valve being rotated in the nextalternate position in response to each vacu whereas the main controlvalve is responsive only to which follows the end of the toppingoperation.

Mum X U3 3 5w HBM M 6 1 8 8 Bmmw 7"" mmoo m nflz m" mm6 m m mm mnm mmomm A m .mflm, mmw R m I: m 4 n 5 "w 9 1 u I LM 5 C a m l] l. n 0 6 6 555 Ill 2 PATENTEUJuN2219n SHEET 3 [1F 3 AUTOMATIC DISPENSING NOZZLE Thepresent invention relates to automatic fuel dispensing and moreparticularly to a nozzle which is automated to the extent of controllingboth the filling and topping operations nonnally encountered in thefilling of vehicle fuel tanks, followed by ultimate shutoff when toppingis completed As explained in our copending US. application, Ser. No.821,366, a typical tank filling operation requires a fuel flowsufficient to enable reasonably prompt service without blowback.Typically, however, as filling reaches, for example, within one or twogallons of completion, sudden constriction produces a characteristicback surge in the filler pipe, which, with a conventional dispensingnozzle, actuates means to shut off the main flow valve of the nozzle andthus terminate flow.

After this initial surge has subsided the tank will still ordinarilyaccept additional fuel at a lower feed rate. This step is referred to as"topping off," a practice which may be onerous to an employee and mayentail spillage.

The present invention concerns a nozzle effective to conduct this seriesof operations automatically. It, in general, involves an improvement inthe invention disclosed and covered by our US. Pat. application, Ser.No. 821,364, filed May 2, 2, 1969 wherein an automatic shutoff nozzle,having a main control valve, is also provided with a flow-regulatingvalve in the main conduit, which is controlled by the initial back surgeof fuel in the filler pipe for actuation from normal open flow positionto a flow-restricting position.

In the flow-restricting position the valve restricts or regulates theflow to a lesser, predetermined topping" rate at which back surge in thefiller pipe does not occur.

Also the flow-regulating valve 50 simultaneously controls thesurge-responsive mechanism that the initial surge of fuel in the fillerpipe triggers actuation of the flow-regulating valve to the exclusion ofthe main control valve. When, however, the flow-regulating valve is inthe second or topping position, the surge-responsive mechanism is socontrolled that the ultimate or final rise of fuel in the filler pipe atthe termination of the topping operation controls or triggers actuationof the main control valve to cut off all flow and finally terminate theoperation.

Ordinarily the surge-responsive control is effected as the result of asuction normally induced, as is well known, by the flow of fuel butvented near the end of the nozzle. When, however, the vent is covered bya surge of fuel, the vacuum is no longer relieved and a suction surge orsignal is sharply builtup.

Reference is made to our aforementioned US. Pat. application Ser. No.821,364 for a detailed description of said development in its broadaspect, and such disclosure is accordingly made a part hereof.

The present invention involves a modification of the foregoing inventionwherein said flow-regulating valve comprises a rotatable valve memberdisposed in the main fuel flow conduit and capable of being indexedalternately in a full flow and a low flow position. The successivedisposition in the two respective flow positions is effected in responseto the suction signal setup as above.

The valve rotor is provided with two separate channels, both of whichpreferably take a generally spiral of turbinelike path with reference tothe axis of the rotor, and which are sharply different in fiow capacity.Thus, in the first, or full flow position, the large channel whichexerts little or no restrictive efi'ect upon the fuel flow, is alignedwith the outlet port.

In the second or low-flow position, the other channel, which is greatlyrestricted in section, is aligned with the outlet pot, thus limitingflow to a low rate, or dribble.

By virtue of the spiral arrangement of the channels the valve tends tobe rotated toward the succeeding operative position by the flow of fueltherethrough so that upon release of the indexing mechanism itautomatically moves toward the succeeding position.

One advantage of the present invention is that with the cessation offlow through the respective channel, the rotational influence ceases sothat until the indexing mechanism comes into play there is a delay inthe rotation of the valve and accordingly a cessation of flow for aperiod of time that may be predetermined and controlled.

Another advantage of the present invention, as previously intimated, isthat the rotary valve also performs the separate function of sodirecting the vacuum impulse or signal as to direct it appropriately tocontrol of the rotational flow regulating valve and/or the final maincontrol valve, as the case may be.

Referring now to the figures of the attached drawing wherein theinvention is illustrated in terms of one specific embodiment thereof:

FIG. 1 is a side elevation of the nozzle of the present inventionlocated in operative position in a vehicle fuel tank,

FIG. 2 is a detailed vertical elevation with major parts broken away toexpose the interior in vertical section,

FIG. 3 is an enlarged detail view centrally through the How regulatingvalve portion of the nozzle,

FIG. 4 is a vertical section taken on the line 4-4 of FIG. 3,

FIG. 5 is a sectional elevation taken on the line 5-5 of FIG.

FIG. 6 is a fragmentary sectional elevation taken on the line 6-6 ofFIG. 2,

FIGS. 7 8r 8 are diagrammatic representations of the indexing mechanismof the flow control valve illustrating the action thereof in aligningthe valve in successive, alternate positions.

The illustrative embodiment of the present invention is based upon amodification of the form of automatic dispensing nozzle shown in US.Pat. No. 2,582,195, which patent is referred to for the detaileddescription of such parts thereof as are common to the present device.

It has, as shown in FIGS. 1 and 2, a preferably cast housing 4 and aprojecting spout 6 which may be placed into a vehicle fuel tank 3. Thecast housing or body 4 has a normally closed main valve 5 therein, avalve lever 7 fulcrumed as at 8 and a pressure responsive diaphragmmechanism 9. As is known, with liquid flowing through the nozzle, thediaphragm mechanism 9 is arranged to trip or release fulcrum 8 so thatmain valve 5 may be automatically closed when the discharge end of thenozzle is submerged in liquid.

Valve 5 is urged to its seat 13 by spring 10 and is provided with valvestem 14 which extends through a packing gland 15 so that its lowerextremity can be engaged by hand lever 7 to lift valve 5 off its seat.Fulcrum 8 is supported by a yoke 16 fastened to the lower end of alockout plunger 17 and normally held in fixed position by a lockingmechanism comprising a plurality of balls 18. These are nested in radialopenings in the plunger and held against an annular shoulder on theinterior of sleeve 20 by a pin 24 fastened to the underside of diaphragm9. The pin is provided with a tapered portion just below the balls sothat when the pin is raised against spring 25 as by application ofsuction to the upper portion of diaphragm 9, the balls 18 will bereleased from the locking shoulder. When the valve 5 has been opened byaction of the hand lever 7, the overriding force applied by therelatively heavy valve spring 10 will drive the fulcrum 8 downwardlyuntil valve 5 is closed.

FIG. 1 shows a latch 22 pivoted as at 23 so that it can be en gaged withthe extremity of lever 7 to hold the valve in open position (which latch22 has been removed in FIG. 2 to more clearly show the details of thepresent invention).

Diaphragm 9 is actuated by suction normally induced by a venturiarrangement 26 just below main valve 5 and operated by the flow ofliquid thru the main valve. I

The suction is normally relieved by vent 28 at the extremity of thenozzle 6, which communicates thru internal tube 30 with the venturichamber 26. Therefore no significant suction can build up until vent oraperture 28 is covered by a surge of liquid. When this happens however,the suction or low pressure surge, if applied to the upper surface ofdiaphragm 9, will raise pin 24 to release the lockout fulcrum asdescribed above.

Relatively light spring 32 urges the lockout plunger 117 back intonormal position shown in FIG. 2 at all times when the valve 5 is closedand the relatively heavy main valve spring is, therefore, not inoverriding position.

At this time also, diaphragm spring brings diaphragm 9 and accordinglythe central pin 24, downwardly into the recess in the lockout plungerand between the balls 14 to force them out outwardly against theshoulder in the sleeve 20 to positively lock the fulcrum 8 in theposition shown.

Referring now to the rotary, flow-regulating valve which is the mainfeature of the present invention, this, as shown in FIGS. 2 and 3, isarranged in the right hand or inlet portion of casting 4. The valvereceives the incoming fuel from hose 34 of Fig. 6 which enters coupling35 on the rear portion of the handle 36. Therefore the incoming fuelpasses thru inlet channel 35 in the handle into chamber 46. Valve rotor42 comprises a cylindrical main body portion with a forward extremity 43which is conical in shape.

As viewed in Fig. 3, the entering fuel from valve chamber passes thruslightly spirally arranged channel 44 formed in the surface of the valverotor thru which the fuel is conducted to outlet channel or port 46. Theoutlet channel 46 leads to the upstream side of valve 5 previouslydescribed.

Channel 44, as shown more clearly in H6. 4, forms a conduit ofrelatively large dimension as contrasted with a second somewhat spirallyarranged channel formed on the opposite side of said valve rotor andindicated by the reference numeral 48.

More specifically, the dimensions of the larger channel or conduit 44areso selected as to accommodate a relatively large flow of fuel throughthe through without material restriction so that the fuel tank may befilled promptly and effectively. The dimensions of conduit 45, on theother hand, are specifically constricted to a suitable topping rate as,for example, 1-3 gallons per minute.

Moreover valve rotor is specifically constructed and arranged in amating recess in the housing 4 so that it rotates freely about its axis.A layer of antifriction material, such as teflon, is preferably providedaround its peripheral surface for this purpose.

Rotation is normally prevented by sleeve 52, integral with valve rotor42, which extends coaxially from the rotor through packing gland 54 andinto chamber 55. The sleeve 52 is internally recessed to freely receivethe extremity of a control rod 56. Moreover bar 56 is provided withopposite radially extending pins 57, engageable within axial slots 59,in the end of shaft 52 so as to index the shaft in either of twopredetermined rotational positions, namely and to with, a first positionwherein the large conduit 44 is aligned with port 46 and the secondposition wherein the relatively restricted conduit 48 is aligned withport 46.

Rod or bar 56 slidably passes thru web 58 in casting 4, in which regionthe rod and the aperture in the web preferably have any convenientpolygonal form as at 63 to resist rotation of the bar 56. Axialactuation of the rod 56 to permit disengagement of pins 57 from slots 59is controlled by diaphragm 60 to which it is fastened as shown. Moreoverthe diaphragm, and accordingly the bar, is normally held in the positionshown in Fig. 3 by coil spring 61, at which time the radial pins 57engage within the slots 59 of the sleeve or shaft 52, specifically shownin Fig. 7 in order to hold or index the rotor 42 in one of the twoaforesaid rotational positions.

Diaphragm 60 and spring 61 are retained by cap 62 as shown, and aninternal conduit 64 connects with the chamber inside of the cap totransmit the vacuum surge or so-called signal to actuate the diaphragmand shift the bar 56 to the right against spring 61, so as to withdrawpins 57 from the mating recesses 59.

Referring now to the dual control mechanism by which the valve 42performs the additional function of coordinating the vacuum signal withthe controlled fluid flow, it is to be noted that a conduit in thehousing 4, indicated by the reference numeral 66 leads directly from theaforementioned venturi chamber 26 to the apex or extremity of thefrustoconical portion 43 of valve rotor. There it is continuouslyaligned with internal axial passageway 67 in the nose of the rotor. Thisaxial passageway 67 terminates in transverse or diametral passageway 68.Moreover the surface of the frustoconical portion 43 about theextremities of the diametral passageway 68 is provided with an annularrecess or groove 69, so that regardless of the radial position at whichthe rotor 43 may find itself, the radial passageway 68 and accordinglypassageways 67 and 66 back to the venturi mechanism are always incommunication with the aforementioned passageway 64 in housing 4.Therefore the chamber 65, formed by cap 62 and the diaphragm 60 which,in turn, controls the indexing mechanism of the rotary valve 42, is atall times in communication with the source of vacuum. Accordinglywhenever the rise of fluid about vent 25 sets up a vacuum surge orsignal, the signal is instantly transferred to the diaphragm, andaccordingly indexing rod 56 is shifted to the right as in Fig. 8 andtherefore out of the indexing slots 59 in shaft or sleeve 52.

Since, at this time, main valve 5 is open, valve 42 will be rotated bythe spiral or turbinelike flow of fuel through conduit 44, moving saidrotor 42 about its axis until flow channel 44 is out of registry withoutlet 46. Thereafter the flow ceases and the vacuum is released,whereupon spring 61 urges rod 56 back into the succeeding valve indexingor locating position. Due to the converging sides of the recess 59 insleeve 52 the pins 57, as rod 56 is returned to the left by the actionof spring 611, cause sleeve 52 and therefore rotary valve 42 to berotated to the second position. More specifically the pins 57, as theymove to the left, ride along the cam surface 75 of the recess to rotatethe sleeve and accordingly the valve 42 into the secondary rotationalposition determined by the location of the pins 57 in the bottom of therecesses 59.

Referring now to the actuation of lockout plunger 17 controlling themain valve, this is effected by a vacuum signal which reaches thechamber above the diaphragm 9 via passageway 76. Passageway 70 is acontinuation of passageway 71 as shown, which terminates in a portopening to the frustoconical surface of the rotor 43 at a pointintermediate between the apex thereof and the end of passageway 68 asshown more clearly in FIG. 3.

Communication of the passageways in rotor 42 with the aforementionedport is effected by passageway or bore 72 which extends radially fromthe central passageway 67 to a point on the surface of the rotor, which,as indicated in FIG. 3, is so rotationally positioned so that it is onlyaligned with passageway 71 when the rotor is in its so-called secondaryposition, namely when the fuel is passing through the restricted conduit45.

Therefore when the parts are as shown in FIGS. 2 and 3, with the majoror full flow passageway 44 in control, a vacuum signal transferred viapassageway 66 goes via passages 67 and 64 to control the rotationalposition of the flow control valve 42, but cannot and does not reach themain shutoff valve.

When however, the rotor is moved through so that restricted passageway48 controls the flow of fuel, then the vacuum signal also passes by wayof passageways 66, 67, 72, 71 and 70 to actuate the diaphragm 9 andrelease fulcrum 8 to close main valve.

In operation, the operator lifts lever 7 about pivot 6 to lift valvestem and open valve 5, holding the valve in open position by engagementof the free end of the lever with pivoted latch shown in FIG. 1, as isconventional.

At this time the fuel from line 34 passes through coupling 35 and inletchannel 38 into rotary valve 42 which, at this time, is indexed in itsnormal full open or first position, that is to say, with the largechannel 44 aligned with outlet port 46. Therefore the fuel flows at asubstantial rate, for example, from 4 up to 10-12 gallons per minutethrough nozzle 6 into fuel tank 3.

The action of the venturi 26 is continually relieved via flow line 30and vent 28, until the initial surge of fluid about the end of spout 6covers vent 28 and transmits a surge of vacuum via ducts 66, 68 and 64into the chamber beyond diaphragm 60, drawing rod 56 to the right asviewed in FIGS. 2 and 3, thereby retracting pins 57 from the indexgrooves 59in sleeve 52, and releasing valve rotor 42.

The spiral flow of the fluid through passageway 44 therefore rotatesrotor 42 counterclockwise, as viewed in H6. 4 until the downstreamextremity of duct 44 passes beyond port 46. At this point therefore flowthrough valve 5 ceases and with it the venturi effect at 26. Theresulting loss of suction brings the chamber beyond diaphragm 60 back toatmospheric pressure so that spring 61 returns rod 56 to the left, thepins 57 engaging in the relatively wide mouths of the two index slots 59to rotate the sleeve or shaft 52 precisely into the aforesaid secondposition wherein the smaller channel or duct 48 is now aligned with port46.

Accordingly therefore the flow through the nozzle resumes at a lower ortopping" rate as, for example in the range of up to about 2-4 gallonsper minute.

Now therefore, when the fuel finally and for the second time rises aboutvent 28 at the end of the topping operation, a vacuum signal in chamber26 is transmitted thru passages 66, 67 and 72 to passageway 71 which isnow in registry therewith.

This, in turn, carries the vacuum signal to the chamber above maindiaphragm 9 via passageway 70 where, as previously explained, retractionof pin 24 releases locking balls 18 and drops the entire lockout fulcrumso as to permit valve 5 to close. Since this simultaneously releases theextremity of the lever 7 from engagement with latch 22, the system isshut off and, as previously pointed out, the lockout plunger 17 and theassociated parts immediately return to original position.

Also since ducts 67 and 68 are always in communication with passageway64, the same vacuum signal simultaneously actuates diaphragm 60 toretract rod 56 and pins 57 and 54, and thus permit the valve 42 to berotated back into original full flow position.

Furthermore the functions taking place as the rotary valve shifts fromits first to its second position provide time for the initial surge offuel about the nozzle to subside so that restricted flow can thenproceed with an open vent 28.

We claim: 1

1. In an automatic dispensing nozzle for supplying liquid fuel to thefiller pipe of a fuel tank and having a supply conduit for said liquid,terminating in a filler spout, a main control valve in said conduit,releasable means for holding said main valve in open position, vacuumresponsive means acting through said holding means for closing said mainvalve and means responsive to a surge of fluid about said spout forcreating a vacuum impulse; the improvement which comprises,

a rotary flow-regulating valve in said conduit, said flowregulatingvalve being rotationally movable between a first, full flow valveposition wherein said fuel flow passes therethrough with relatively lowrestriction, and a second, partial flow position wherein said fuel flowis restricted to a predetermined relatively low filling rate,

indexing means responsive to a vacuum signal from said surge responsivemeans for successively locating and fixing said rotary valve in theaforesaid respective positions,

such that an initial vacuum impulse effects rotation of said valve fromfirst position to said second position and wherein any subsequent vacuumimpulse causes the valve to return to its first position and means forcommunicating said subsequent vacuum impulse with said vacuum responsivemeans to effect closure of said main valve, thus terminating the fillingoperation.

2. An automatic dispensing nozzle as called for in claim 1 wherein saidrotary flow-regulating valve conducts said fuel flow through passagewayswhich run spirally to effect a turbine action such that upon release ofsaid indexing means the valve is rotated by the residual flow of fluidtoward the succeeding position.

3. An automatic dispensing nozzle as called for in claim 2 wherein saidindexing means comprises a member withdrawn in response to said vacuumsignal to release said valve for rotation, said member, upon terminationof said vacuum signal returning to align and rotationally fix saidrotary valve in a succeeding rotational position.

4. An automatic dispensing nozzle as called for in claim 3 wherein saidindexing mechanism comprises cooperating pin and notch means providedwith a cam surface adapted to align the rotary flow-regulating valve insaid position.

5. In an automatic dispensing nozzle for supplying liquid fuel to thefiller pipe of a fuel tank, such nozzle having an internal supplyconduit terminating in a filler spout, a main control valve in saidconduit, releasable latching means for holding said main valve in openposition, vacuum responsive means acting through said holding means forreleasing said main valve, and means responsive to a rise of fluid aboutsaid spout for creating a vacuum impulse; the improvement whichcomprises a flow-regulating rotary valve disposed in said conduit, saidrotary valve having separate fluid supply ducts therein, adapted to bealigned selectively in said supply conduit,

means positively indexing said rotary valve in a first rotationalposition wherein a relatively large fuel supply duct is aligned withsaid conduit,

said indexing means being adapted alternately thereafter to positivelyfix said rotary valve in a second operative position wherein arelatively restricted flow channel is aligned with said conduit,

means responsive to a first vacuum impulse for actuating said indexingmeans to cause the rotary valve to move to said second operativeposition, and

means efi'ective only when said rotary valve is in said second positionto conduct any subsequent vacuum surge to said vacuum responsive releasemeans for closing said main valve.

6. An automatic dispensing nozzle as called for in claim 5 wherein saidlast named means comprises a vacuum impulse duct in said rotary valve incommunication with said vacuum impulse creating means and a portassociated with said valve and arranged in alignment with said duct onlywhen said rotary valve is in said second position, said last named portcommunicating with said vacuum responsive means for closing said mainvalve.

Patent No. 3,5 73 Dated June 22, 1971 Inventor) Eugene W. Vest & Dean C.McGahey It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

['"In the specification: '1

Col. 1, line 23 change"2,2"to -2- Col. 1, line 61 change "of" secondoccurrence to -01" Col. 1, line 67 change "pot"'to -port-- Col. 3, 11 re8, delete "out" 001. 3, line 32, change "through" (second occasion) to--nozzle-- Col. 3, line +8, change "with" to --wit- Signed and sealedthis 7th day of December 1 971 (SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTISCHALK Attesting Officer ActingCommissioner of Patents

1. In an automatic dispensing nozzle for supplying liquid fuel to thefiller pipe of a fuel tank and having a supply conduit for said liquid,terminating in a filler spout, a main control valve in said conduit,releasable means for holding said main valve in open position, vacuumresponsive means acting through said holding means for closing said mainvalve and means responsive to a surge of fluid about said spout forcreating a vacuum impulse; the improvement which comprises, a rotaryflow-regulating valve in said conduit, said flowregulating valve beingrotationally movable between a first, full flow valve position whereinsaid fuel flow passes therethrough with relatively low restriction, anda second, partial flow position wherein said fuel flow is restricted toa predetermined relatively low filling rate, indexing means responsiveto a vacuum signal from said surge responsive means for successivelylocating and fixing said rotary valve in the aforesaid respectivepositions, such that an initial vacuum impulse effects rotation of saidvalve from first position to said second position and wherein anysubsequent vacuum impulse causes the valve to return to its firstposition and means for communicating said subsequent vacuum impulse withsaid vacuum responsive means to effect closure of said main valve, thusterminating the filling operation.
 2. An automatic dispensing nozzle ascalled for in claim 1 wherein said rotary flow-regulating valve conductssaid fuel flow through passageways which run spirally to effect aturbine action such that upon release of said indexing means the valveis rotated by the residual flow of fluid toward the succeeding position.3. An automatic dispensing nozzle as called for in claim 2 wherein saidindexing means comprises a member withdrawn in response to said vacuumsignal to release said valve for rotation, said member, upon terminationof said vacuum signal returning to align and rotationally fix saidrotary valve in a succeeding rotational position.
 4. An automaticdispensing nozzle as called for in claim 3 wherein said indexingmechanism comprises cooperating pin and notch means provided with a camsurface adapted to align the rotary flow-regulating valve in saidposition.
 5. In an automatic dispensing nozzle for supplying liquid fuelto the filler pipe of a fuel tank, such nozzle having an internal supplyconduit terminating in a filler spout, a main control valve in saidconduit, releasable latching means for holding said main valve in openposition, vacuum responsive means acting through said holding means forreleasing said main valve, and means responsive to a rise of fluid aboutsaid spout for creating a vacuum impulse; the improvement whichcomprises a flow-regulating rotary valve disposed in said conduit, saidrotary valve having separate fluid supply ducts therein, adapted to bealigned selectively in said supply conduit, means positively indexingsaid rotary valve in a first rotational position wherein a relativelylarge fuel supply duct is aligned with said conduit, said indexing meansbeing adapted alternately thereafter to positively fix said rotary valvein a second operative position wherein a relatively restricted flowchannel is aligned with said conduit, means responsive to a first vacuumimpulse for actuating said indexing means to cause the rotary valve tomove to said second operative position, and means effective only whensaid rotary valve is in said second position to conduct any subsequentvacuum surge to said vacuum responsive release means for closing saidmain valve.
 6. An automatic dispensing nozzle as called for in claim 5wherein said last named means comprises a vacuum impulse duct in saidrotary valve in comMunication with said vacuum impulse creating meansand a port associated with said valve and arranged in alignment withsaid duct only when said rotary valve is in said second position, saidlast named port communicating with said vacuum responsive means forclosing said main valve.